Achieve ultrahigh energy storage performance in BaTiO₃–Bi(Mg_1/2Ti_1/2)O₃ relaxor ferroelectric ceramics via nano-scale polarization mismatch and reconstruction

Development of lead-free dielectric ceramics with large recoverable energy storage density (W_rec), high energy storage efficiency (η) and wide usage temperature range is of great significance to improve the overall performance of power electronic devices. Despite the numerous research efforts, performance of existing lead-free dielectric ceramics is barely satisfactory. Herein, an effective strategy to achieve ultrahigh energy storage performance via nano-scale polarization mismatch and reconstruction is proposed. By developing solid solutions of A-site coupling and B-site coupling ferroelectrics, polarization mismatch and ultrahigh energy storage performance can be realized in intermediated compositions. It is demonstrated that ultrahigh energy storage performance with a η of 93% and a W_rec of 4.49 J/cm³ is achieved in the 0.6BaTiO₃-0.4Bi(Mg_1/2Ti_1/2)O₃ (0.6BT-0.4BMT) ceramic, which is a record high energy storage property in lead-free relaxor ferroelectric bulk ceramics. Excellent temperature stability with a variation of W_rec and η less than 5% is also realized in a wide temperature range from 30 °C to 170 °C. Such an ultrahigh energy storage performance not only verifies our strategy, but also makes the 0.6BT-0.4BMT ceramic a promising candidate material for energy storage. Moreover, of particular significance is that this work provides an effective method to design novel high performance dielectric ceramics for future energy storage devices.